<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>弹性布局</title>
    <style>
        div{
            width: 100%;
            height: 150px;
            background-color: rgb(128, 0,0);
            display: flex;
            justify-content:space-around;
            align-items: center;
        }

        span{
            width: 100px;
            background-color: rgb(0, 128,0);
            display: block;
        }
    </style>
</head>
<body>
    <div>
        <span>1</span>
        <span>2</span>
        <span>3</span>
    </div>
</body>
</html>